DETECTION OF BOVINE RESPIRATORY SYNCYTIAL VIRUS IN CALVES OF RIO GRANDE DO SUL, BRAZIL

DETECÇÃO DO VÍRUS RESPIRATÓRIO SINCICIAL BOVINO EM TERNEIROS NO RIO GRANDE DO SUL, BRASIL

DETECTION OF BOVINE RESPIRATORY SYNCYTIAL VIRUS IN CALVES OF RIO GRANDE DO SUL, BRAZIL¹

DETECÇÃO DO VÍRUS RESPIRATÓRIO SINCICIAL BOVINO EM TERNEIROS NO RIO GRANDE DO SUL, BRASIL

SHORT NOTE

Ivan Paulo Demartini Gonçalves² Agda Theisen Simanke³ Heidy Christine Jost³ Isidro Hôtzel³ Adriana Dal Soglio³ Valéria Moojen⁴

RESUMO

Durante 20 meses entre 1987 e 1990 coletou-se, em matadouro, amostras de tecido pulmonar de 351 torneiros originários de municípios próximos à Porto Alegre. Utilizando-se a imunofluorescência direta (IFD) e indireta com anticorpos policlonais e monoclonais em cortes de pulmão congelados verificou-se a presença do Vírus Respiratório Sincicial Bovino (BRSV) em 18 (5,13%) das amostras. Isolou-se o BRSV de amostras positivas pela IF.

Palavras-chave: vírus respiratório sincicial bovino - imunofluorescência.

SUMMARY

During 20 months of the 1987-1990 period, lung tissue samples from 351 calves were obtained at a slaughterhouse. These calves were from counties nearby Porto Alegre. The direct and indirect fluorescent antibody tests (FAT) using polyclonal and monoclonal antibody conjugates were performed on frozen lung sections. Eighteen (5.13%) of the calf lung samples were positive for the Bovine Respiratory Syncytial Virus (BRSV). The BRSV was isolated from FAT positive samples.

Key words: bovine respiratory syncytial virus, immunofluorescence.

Bovine Respiratory Syncytial Virus (BRSV) causes a severe bovine respiratory disease and is most often associated with fatal pneumonia in calves. In England it had a seasonal pattern of infection, i.e., autumn and winter (EDWARDS et al, 1984).

Employing the serum-neutralization test and a modified fluorescent antibody test (DFAT) in Canada, it was found that 71.3% of calves had antibodies against BRSV. When these tests were applied to adult cattie, 95% were found to be positive (MARTINS & BOHAC, 1986; LYNCHS & DERBYSHIRE, 1986).

In England, 6.4% of the bovine pneumonic lungs examined by the DFAT were positive to BRSV, and also 50% of the samples from five pneumonia outbreaks (EDWARDS et al, 1984; THOMAS & STOTT, 1981).

The first isolation in France, of the BRSV from dairy cows was first reported in 1986 (FRAPPIER et al, 1986).

VAN VUUREN (1990) reported antibody titres to BRSV ranging from 10 to 1280 during an outbreak of respiratory tract infections in cattie kept in feedlots in South Africa.

The SCOTTISH VETERINARY INVESTIGATION SERVICE (1991) reported a rise in the number of submissions relating to respiratory problems in cattie in December 1990; BRSV infection was the most common diagnosis. It was found primarily in young animals. The fluorescent antibody test (FAT) is considered to be rapid and effective in detecting BRSV in bovine specimens CTHOMAS & STOTT, 1981).

Recently, it was found that an enzyme immunoassay, designed to detect human respiratory syncytial virus antigens in human samples, may permit a rapid diagnosis in bovine samples with greater sensitivity than the DFAT, a BRSV specific monoclonal antibody conjugate was used (OSÓRIO et al, 1989).

During the months of April to November 1987 and April 1989 to March 1990, lung tissue samples from 351 calves were collected at a slaughterhouse nearby Porto Alegre city, Rio Grande do Sul, Brazil. The calves were approximately few days to some weeks old and were culled from small dairy farms.

The direct and indirect FAT using polyclonal and monoclonalb antibody conjugates were performed on the frozen lung sections of 6-8µm. Eighteen (5.1%) of the calf lung samples were positive for BRSV (Table 1).

Viral isolation attempts were performed on 5 lung tissue samples that were positive by the FAT; These lung samples were homogenized and inoculated onto monolayers of calf testis secondary cell cultures. The cytopathic effect (CPE) including syncytia and cytoplasmic inclusions, and a positive FAT were observed on the third post-inoculation day on 3 samples. The cell cultures employed as controls were negative for CPE and did not show secific fluorescence.

This appears to be the first report of BRSV infection of calves in Brazil. It strongly indicates that BRSV respiratory infections are prevalent in Brazil and that the causal agent should be sought when investigating Bovine Respiratory Disease Complex.

SOURCES AND MANUFACTURERS

Central Veterinary Laboratory - Weybridge. UK. Rhöne-Mérieux - Lyon, France.

²Médico Veterinário, Bolsista de Aperfeiçoamento CNPq;

³Acadêmicos do Curso de Medicina Veterinária da Universidade Federal do Rio Grande do Sul (UFRGS), bolsistas de Iniciação Científica CNPq.

⁴Médico Veterinário, MSC, Professor Adjunto IV - Departamento de Patologia Clínica Veterinária-Laboratório de Virologia-Faculdade de Medicina Veterinária da UFRGS. Caixa Postal 2172. 90001-970 - Porto Alegre, RS - Pesquisador do CNPq.

Recebido para publicação em 26.04.93. Aprovado para publicação em 12.05.93.

• EDWARDS, S., NEWMAN, R.H, STANLEY, M. Respiratory syncytial virus diagnosis. Vet Rec, v. 114, n. 4, p. 101, 1984.
• FRAPPIER, E., LUCAS, C., SERRANO, S. et al. Isolement d'un virus respiratoire syncytial bovin en France. Rec Med Vet, v. 162, n. 11, p. 1189-1194, 1986.
• LYNCH, J.A, DERBYSHIRE, J. B. Application of a modified indirect fluorescent antibody test to the detection of antibodies to bovine respiratory syncytial virus in Ontario cattle. Can J Vet Res, v. 50, p. 384-389, 1986.
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• OSORIO, F.A., ANDERSON, GA, SANDERS, J. et al. Detection of bovine respiratory syncytial using a heterologous antigen-capture enzyme immunoassay. J Vet Diagn Invest, v. 1, p. 210-214, 1989.
• SCOTTISH VETERINARY INVESTIGATION SERVICE. Respiratory problems in cattle rise in december. Vet Rec, v. 128, n. 12, p. 268, 1991.
• THOMAS, L.H., STOTT, E.J. Diagnosis of respiratory syncytial virus infection in the bovine respiratory tract by immunofluorescence. Vet Rec, v. 108, p. 432-435, 1981.
• VAN VUUREN, M. Bovine respiratory Syncytial Virus in South Africa. J South Africa Vet Assoc, v. 61, n. 168, 1990.

¹

This Project was supported by the CNPq Grant nº 413240-88.6/VT/FV/PQ.

Publication Dates

• Publication in this collection
  03 Sept 2014
• Date of issue
  Dec 1993

History

• Accepted
  12 May 1993
• Received
  26 Apr 1993